Author:
Castell A. G.,Cliplef R. L.
Abstract
Landrace-sired progeny (B-boars, G-gilts and CM-castrates) were obtained from sows in two Hampshire lines (Control, Select) derived by applying a selection index which had three times the emphasis on backfat reduction than on post-weaning growth to 90 kg. Experiment 1 used 72 pigs from the Generation 1 sows and a split-plot design with line as the main plot and sex-type as the sub-plot. A 16% CP diet was fed, ad libitum, in the 24 pens over the period from 26 to 100 kg liveweight. No significant (P < 0.05) differences in live performance or carcass measurements were found between pigs from the two lines. However, characteristic differences among the sex types were observed, e.g., the slower growth by G, higher intake by CM and superior gain:feed by B. Experiment 2, following the same format with Generation 5 progeny (N = 90 and 30 pens), revealed a difference (P < 0.01) in daily intake (ADI) relative to liveweight (LWT) between Control (ADI = 123 × LWT0.729; R2 = 0.89, P < 0.01) and Select (ADI = 123 × LWT0.716; R2 = 0.84, P < 0.01) pigs. The lack of significant differences for other live and carcass criteria could be explained if the index was favouring individuals with low appetites and reducing the potential for high rates of lean tissue deposition in the Select pigs. Growth of all the pigs from birth to market weight, examined by correlation and regression analyses, suggested that pre-test feeding practices were also limiting the attainment of maximum rates of lean tissue deposition. Key words: Pig, selection index, growth rate, carcass, appetite
Publisher
Canadian Science Publishing
Subject
Animal Science and Zoology,Food Animals